ISession session = NhibernateSessionFactory.openSession();
IQuery c = session.CreateQuery("from users users join users.certificate");
dataGridView1.DataSource = c.List();

  private void Form1_Load(object sender, EventArgs e)
        {
           ISession session = NhibernateSessionFactory.openSession();
           this.BindUsers();
          
        }

        private void BindUsers()
        {
            usersDao usersDao = new usersDao();
            List<users> user = usersDao.GetAll(); 
            dataGridView1.DataSource = user;
            cmbUsers.DataSource = user;
            cmbUsers.DisplayMember = "NameUser";
        }

namespace SessionFactory
{
    public class usersDao : BaseDao
    {
        public usersDao()
        {

        }
        public List<users> GetAll()
        {
            List<users> usersList = new List<users>();
            IList result = GetItems(typeof(users));
            foreach (users c in result)
                usersList.Add(c);
            return usersList;

        }


    }

}

using System;
using System.Collections.Generic;
using System.Text;
using NHibernate;
using Domain;
using System.Collections;

namespace SessionFactory
{
    public class BaseDao
    {

        public virtual IList GetItems(Type type)
        {
            IList items = null;
            ISession session = NhibernateSessionFactory.openSession();
            ITransaction tr = null;

            tr = session.BeginTransaction();
            items = session.CreateCriteria(type).List();
            tr.Commit();
            return items;
        }
    }
}